1. Technical Field
The present disclosure relates to a method of manufacturing toner, an apparatus for manufacturing toner, and a method of manufacturing resin particle.
2. Description of Related Art
Pulverization methods are generally known as toner manufacturing methods. In a pulverization method, toner constituents are melt-kneaded by double rolls or a double-axis extruder. The kneaded product is pulverized into coarse particles and the coarse particles are pulverized into fine particles. The fine particles are classified by size and the desired-size particles are collected. The collected particles are further mixed with an external additive, such as a fluidizer, by a HENSCHEL MIXER, if needed. The coarse pulverization can be performed by an instrument such as ROATPLEX and PULVERIZER. The fine pulverization can be performed by an instrument such as JET MILL and TURBO MILL. The classification can be performed by a wind power classifier such as ELBOW-JET CLASSIFIER.
Atomization methods are also known as toner manufacturing methods. In an atomization method, a toner constituents liquid is formed into liquid droplets in a gas phase by the use of an atomizer, such as single-fluid nozzle (pressurized nozzle) atomizer, multi-fluid spray nozzle atomizer, and rotating disc atomizer. The single-fluid nozzle atomizer is configured to atomize a liquid from nozzle holes by application of pressure. The multi-fluid spray nozzle atomizer, such as two-fluid or four-fluid spray nozzle atomizer, is configured to atomize a mixture of a liquid and a compressed gas. The resulting liquid droplets are finer than those resulting from the single-fluid nozzle atomizer. The rotating disc atomizer is configured to form a liquid into liquid droplets by centrifugal force from a rotating disc. The atomization methods can be generally performed by commercially available spray dry systems which are configured to perform atomization and drying simultaneously. When drying by the spray dry system is insufficient, the secondary drying, such as fluidized-bed drying, can be performed. The resulting particles are further mixed with an external additive, such as a fluidizer, by a HENSCHEL MIXER, if needed.
It is likely that toner particles produced by the pulverization or atomization method include a large amount of ultrafine particles, which is not preferable. The ultrafine particles should be removed because they contaminate carrier particles (in two-component developer) and a developing device. As the content of ultrafine particles increases, productivity decreases and production cost increases.
Injection granulation methods are also known as toner manufacturing methods. In an injection granulation method, a liquid is formed into liquid droplets by discharging the liquid from nozzle holes having a diameter similar to a target toner diameter by the use of a vibration generator. Japanese Patent Application Publication No. 2007-199463 describes an injection granulation method which forms liquid columns by discharging a toner constituents liquid from a pressure chamber through nozzles upon application of pressure in a certain direction and dividing the liquid columns into liquid droplets upon application of weak ultrasonic vibration. The toner constituents liquid is supplied to the pressure chamber from a toner constituents liquid container. The toner constituents liquid container has an agitation member for generating a flow of the toner constituents liquid. Due to the generated flow, each toner constituents are kept evenly dispersed in the toner constituents liquid. The toner constituents liquid in the pressure chamber is pressurized in a certain direction and formed into liquid columns through the nozzles. The liquid columns are divided into uniform liquid droplets by inducing the Rayleigh fission by applying weak vibration from a vibration generator. The liquid droplets are then solidified into toner particles. When employing the Rayleigh fission, the liquid is discharged from the nozzles due to vibration as well as pressure. Therefore, the vibration generator has to generate only weak vibration with only low voltage.
In the described method, liquid droplets, formed upon application of pressure to the toner constituents liquid in a certain direction, have a diameter about twice the inner diameter of the nozzle. Therefore, the inner diameter of the nozzle should be smaller when forming small-sized particles, which is more likely to cause nozzle clogging due to the pressure.
Japanese Patent No. 3786034 describes another injection granulation method in which a raw material liquid of toner is discharged from a nozzle by uniformly applying pressure to the raw material liquid retained in a raw material retention part. FIGS. 1A to 1E are views for explaining a mechanism of liquid droplet discharge described in the above reference. A raw material retention part 101 repeatedly goes through the following three states so that liquid droplets are intermittently formed. FIG. 1A is a view of the first state in which a discharge signal is not yet input. A piezoelectric body 102 does not deform, the raw material retention part 101 does not change its volume, and therefore the raw material liquid 103 is not discharged from a nozzle 104. FIGS. 1B and 1C are views of the second state in which a discharge signal is input. The piezoelectric body 103 deforms such that the raw material retention part 101 reduces its volume. In the second state, the raw material retention part 101 instantaneously and uniformly increases its inner pressure and thereby discharges a liquid droplet 105 from the nozzle 104. The raw material retention part 101 is communicated with a raw material storing part, not shown, for storing and feeding the raw material liquid 102. FIGS. 1D and 1E are views of the third state in which one liquid droplet has been discharged. Voltage supply is terminated and the piezoelectric body 103 has returned to its original shape. Due to negative pressure in the raw material retention part 101, the raw material retention part 101 is replenished with the raw material liquid 103 from the raw material storing part.
After being replenished with the raw material liquid 103, the raw material retention part 101 needs to go through the first state in which the raw material liquid 103 is not discharged, which reduces toner productivity.
The method generally produces relatively large liquid droplets. Small liquid droplets can be produced only when the nozzle diameter is relatively small or the toner raw material is diluted. It is likely that a small-diameter nozzle is clogged with solid toner constituents, such as pigment and release agent, thereby reducing production stability. A diluted toner raw material requires a greater amount of energy when being dried, thereby also reducing production stability. When production stability is low, the raw material liquid 103 accumulates in the raw material retention part 101 for an extended period of time, resulting in undesirable fixation of toner constituents to production equipments.
In this method, each raw material retention part 101 has only one nozzle. Provision of a plurality of nozzles may increase productivity but may decrease size uniformity of the produced particles.